1. Field of the Invention
A surgical instrument is disclosed, and more particularly relates to a handle for an endoscopic or laparoscopic surgical instrument having reciprocating jaw members which pivot toward and away from each other in response to opening and closing movements of the handle members, where movement of the handle members is translated through an elongated tubular body member to open and close the jaw mechanism. The present invention further relates to a ratchet mechanism which is internally disposed within the handle to provide incremental positioning and selective release of the jaw members in relation to each other.
2. Discussion of the Prior Art
In the prior art, various endoscopic surgical instruments are disclosed which utilize elaborate and complex mechanisms for opening and closing handle members and jaw members to facilitate use of the device at a surgical site. Certain devices are of intricate construction in which a linkage mechanism for opening and closing the jaws requires numerous moving parts, while a sliding arrangement is provided between two extended rod members to activate the linkage mechanism in response to movement of the handle members. Furthermore, it is often necessary for the surgeon, or an assistant, to maintain a constant force on the handles to keep the jaw mechanism closed in the event that the instrument is a grasping or gripping device such as forceps, needle holders, or retractors. This limits the surgeon's range, and in the case of an assistant, often requires additional personnel to be present in the operating room, thus restricting movement in an already confined area.
To alleviate this problem, it has been known to provide locking mechanisms on the handles of the surgical instruments which allow the surgeon to lock or clamp the jaw members in place to free the surgeon's hands to operate additional instruments during the course of the operation. Furthermore, such mechanisms free the surgical assistant to support the surgeon and eliminate the need for additional assistants. Some typical locking devices include arm members which extend between the handles so that a series of ridges or ribs on each arm member engage corresponding ridges on the opposite arm to lock the handles in position. Bending one arm in relation to the other releases the locking mechanism.
One disadvantage associated with these known devices concerns the release of the locking mechanism for subsequent movement of the jaw members to remove or reposition the instrument. Generally, the arm members of locking mechanisms are constructed of a resilient material, such as stainless steel or rigid plastic, and the locking forces which hold the arm members in engagement are generated by the natural flexing and biasing of the material of which the arm members are constructed. To release the locking mechanism, the arms must be disengaged by overcoming the locking forces of the arms. Typically, this is accomplished by manually flexing the arms away from each other, necessitating the use of two hands, one to grasp the instrument, and the other to forcibly move the arm members. This, of course, requires the surgeon (or assistant) to release the mechanism, thereby providing a distraction from the surgeon's primary function. This factor also reduces the effectiveness of the surgeon during the operation, particularly in an emergency.
Another disadvantage of these known devices is that often such typical locking mechanisms cannot be overridden; that is, the mechanism is always engaged, thereby preventing free movement of the handle and jaw mechanism. This usually causes the surgeon to choose an instrument of one type or another, i.e., one having a locking mechanism or one having no locking mechanism. As a result, the surgeon may demand that all types of such instruments are present during an operative procedure thereby lending to an over-abundance of instruments in the operating room and further complicating the procedure.
Lastly, locking mechanisms located on the handles may require particular procedures for sterilization, packaging and storage, as well as in normal handling in the operating room. Unwanted accumulation of debris may clog the ribs of the locking mechanism thus reducing its effectiveness. Additionally, this design may not be suitable for an instrument designed for multiple uses and such clogging may cause damage to the ribs during packaging or storage and may destroy the ribs, rendering the locking mechanism useless.
U.S. Pat. No. 1,452,373 to Gomez discloses a typical locking mechanism for a surgical instrument, in which a plurality of ribs are provided on an extension of the handle member which engage a similar rib member on the opposite handle. Once engaged, the handles must be moved away from each other perpendicular to their longitudinal to disengage the locking mechanism to release the jaw mechanism.
U.S. Pat. No. 4,896,661 to Bogerr et al. disclose a surgical instrument having a ratchet mechanism positioned on the handle members which includes a curved rack member attached to one handle member which passes through a slot in the other handle member. A releasable pawl member is provided on the second handle to engage the rack member and provide a means for releasing the ratchet.
U.S. Pat. No. 4,935,027 to Yoon discloses a surgical instrument having a ratchet mechanism positioned between the handle members. A rack member is provided which extends from one handle and passes through a slot in the second handle to lock the handles in place. Pivoting the rack member away from corresponding grooves in the slot will release the ratchet mechanism.
U.S. Pat. No. 4,428,374 to Auburn discloses a surgical instrument having means for positioning and holding the handle members in relation to each other. A rack member is provided on one handle member which extends through a slot in the second handle member in which a releasable pawl mechanism is provided to engage and disengage the ratcheting mechanism.
The novel surgical instrument disclosed herein overcomes the disadvantages encountered in the prior art and provides a precise instrument which is easy to manufacture and efficient to use, and which eliminates many of the moving parts required by prior art devices. Also, the present instrument incorporates many features which are of use to the surgeon during an operation, including an internal ratcheting mechanism to provide for incremental movement of the tool mechanism and locking of the jaws if desired, while maintaining a lightweight construction in an easy to handle device in which all of the features may be operated with one hand. Furthermore, the features are so positioned so as to provide a maximum line of sight for the surgeon without obstructing the view to the surgical site.